JPH0626076Y2 - Motor control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a motor control circuit that controls the rotation speed of a motor based on an input output signal of a tachometer.

<Prior Art> A tachometer (tachometer) is a measuring instrument for measuring the rotation speed. Generally, when an AC or DC motor is rotated, a voltage proportional to the rotation speed is generated to measure the rotation speed. It is like this. The output voltage of such a tachometer is generally an AC voltage, and it has been necessary to convert the output voltage to a DC voltage in order to incorporate it into the feedback loop of the motor control circuit as described above.
In order to perform such conversion into a DC voltage, a rectifier circuit composed of a diode bridge, a capacitor, and a resistor has been conventionally used.

However, in the above-mentioned conventional example, when the rotation speed of the motor becomes slow and the output voltage of the tachometer becomes equal to or lower than the forward voltage of the diode, the speed output of the motor cannot be output. Further, if the value of the capacitor or the resistance is increased in order to reduce the smooth ripple (pulsation) voltage, the response to the speed change of the motor becomes slow and the control characteristics of the motor deteriorate.

<Problems to be Solved by the Invention> The present invention has been made in view of the drawbacks of the conventional example, and an object thereof is to convert the output voltage of the tachometer into a DC voltage with high accuracy and responsiveness to drive the motor. It is to provide a motor control circuit for controlling.

<Means for Solving Problems> A feature of the present invention for solving the above problems is that a motor control circuit for controlling the rotation speed of a motor based on an input signal of an input tachometer A differential amplifier circuit that receives the output of the tachometer and that removes a common mode voltage component of the output and that amplifies the signal voltage component by a constant factor; and an output from the differential amplifier circuit that includes an operational amplifier. A second idealization that rectifies the first idealized diode-type half-wave rectification circuit for rectifying and a phase inverting circuit that has an operational amplifier and inverts the phase of the output of the differential amplifier circuit, and rectifies the output from the phase inverting circuit A full-wave rectification circuit that includes a diode-type half-wave rectification circuit and takes a sum of outputs of the first idealized diode-type half-wave rectification circuit and the second idealized diode-shaped half-wave rectification circuit, and the full-wave rectification circuit Out of the circuit The in providing the motor control circuit which is formed by including a smoothing circuit of the active filter type for smoothing.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. First
FIG. 1 is a circuit diagram of an embodiment of the present invention, in which 1 is an operational amplifier A ₁ and resistors R _{1 to} R ₄ and receives the output of a tachometer T to multiply the output value, in this case, R ₃ / R ₁ times. A _first half-wave rectification circuit for differentially amplifying the differential amplifier circuit 2 and comprising an operational amplifier A ₂ , resistors R ₅ , R ₆ and diodes D ₁ , D ₂ for half-wave rectifying the output of the operational amplifier A _1. 3 is a differential amplifier A _{1 including an} operational amplifier A ₃ , resistors R ₇ and R _8.
A phase inversion circuit that receives the output of the
Reference numeral 4 is a second half-wave rectifier circuit which is composed of an operational amplifier A ₄ , resistors R ₉ , R ₁₀ and diodes D ₃ , D ₄ for half-wave rectifying the output of the phase inversion circuit 3, and 5 is an operational amplifier A ₅ , An active filter type smoother which includes a resistor R ₁₁ , a resistor R ₁₂ , a capacitor C ₁ , and a capacitor C _{2 and} receives the outputs of the first half-wave rectifier circuit 2 and the second half-wave rectifier circuit 4 and smoothes these outputs. Circuit. The first half-wave rectifying circuit 2, the phase inverting circuit 3, and the second half-wave rectifying circuit 4 constitute an idealized diode type full-wave rectifying circuit.

FIG. 2 is a time chart for explaining the operation of the embodiment of the present invention having the above-mentioned structure, in which A is the output waveform of the tachometer T, B is the output waveform of the differential amplifier A ₁ , and C is the output waveform. Is the output waveform of the first half-wave rectifying circuit 2, D is the output waveform of the second half-wave rectifying circuit 4, E is the input waveform of the smoothing circuit 5, and F is the output waveform of the smoothing circuit 5. In FIGS. 1 and 2, the output of the tachometer T has a voltage waveform in which the signal voltage component e ₁ is superimposed on the common mode voltage component e ₀ as shown in FIG. 2A. When the output of the tachometer T is sent to the amplifier circuit 1 and differentially amplified, the common mode voltage component e ₀ is removed and the signal voltage component e ₁ is amplified (R ₃ / R ₁ ) times. As a result, an output signal e ₂ having a waveform as shown in FIG. 2B is obtained. Such an output e ₂ is
It is sent to the half-wave rectifier circuit 2 and half-wave rectified to become an output signal e ₃ having a waveform as shown in FIG. 2C. Further, the output signal e ₂ is also sent to the phase inverting circuit 3 to be phase-inverted, and then sent to the second half-wave rectifying circuit 4 to be half-wave rectified, and the output signal having a waveform as shown in FIG. 2D. It becomes e ₄ . Here, since the first half-wave rectifier circuit 2 and the second half-wave rectifier circuit 4 are idealized diode type rectifier circuits, the first half-wave rectifier circuit 2, the phase inversion circuit 3, and the second half-wave rectifier circuit When the full-wave rectification circuit consisting of 4 is used, the rotation of the motor is linearly full-wave rectified to near zero. Thereafter, a first output e ₃ of the half-wave rectifier circuit 2 output e ₄ of the second half-wave rectifier circuit 4 becomes the input signal of the smoothing circuit 5, a is smoothed by the smooth circuit 2
The output signal e _{5 has} a waveform as shown in FIG. here,
The smoothing circuit 5 is a second-order active filter type smoothing circuit, and in the case of the same output ripple voltage, the response delay as seen in a normal smoothing circuit composed of a resistor and a capacitor does not occur.

<Effect of the Invention> According to the embodiment of the present invention as described in detail above, a full-wave rectification circuit using an idealized diode is used to linearly rectify the rotation of the motor to near zero. Because of the configuration, there is an advantage that an output corresponding to the speed of the motor can be obtained even when the rotation speed of the motor is slow and the output voltage of the tachometer is low.

In addition, when the ripple voltage is the same, the response delay of the active filter type smoothing circuit is smaller than that of a normal passive type smoothing circuit consisting of resistors and capacitors, so the change in motor speed can be detected faster. There is also.

[Brief description of drawings]

FIG. 1 is a configuration circuit diagram of the embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of the embodiment of the present invention. 1 ... Amplification circuit. 2, 4 ... Idealized diode type half-wave rectifier circuit, 3 ... Phase inversion circuit, 5 ... Smoothing circuit

Claims (1)

[Scope of utility model registration request] 1. A motor control circuit for controlling the rotation speed of a motor based on an input tachometer output signal, wherein the motor control circuit has an operational amplifier and receives an output of the tachometer to remove a common mode voltage component of the output. A differential amplifier circuit that amplifies the signal voltage component by a certain factor, and a first idealized diode-type half-wave rectifier circuit that has an operational amplifier and rectifies the output from the differential amplifier circuit and an operational amplifier The first idealized diode-type half-wave rectification circuit comprising a phase-inverting circuit that inverts the phase of the output of the differential amplifier circuit and a second idealized diode-type half-wave rectification circuit that rectifies the output from the phase-inversion circuit. Circuit, a full-wave rectification circuit that sums the outputs of the second idealized diode-type half-wave rectification circuit, and an active filter-type smoothing circuit that smoothes the output of the full-wave rectification circuit. Data control circuit.